Conveyor assemblies adapted for use in painting booths, embodying conveyor units having upper and lower frames spaced apart by post portions aligned in the direction of travel. A dust cover encloses the drive mechanism and has a top wall between the upper and lower frames. A slot is provided to permit passage of the aligned post portions, and the slot is covered by a resilient flexible flap which can be displaced by the post portions as they travel through the slot. The drive mechanism includes alternative drive chains, one of which has a pusher for effecting advance of the units, the other of which has a bifurcated coupling which may effect both advance and retraction of the units along their path of travel. The lower frame has swivelable wheels which may ride in the elevated wheel-guide tracks in the painting booth to provide stabilization of the frame against lateral sway.

An accumulator mechanism for stopping a carrier on an inverted power and free conveyor system when it approaches a stopped preceding carrier. A pivot arm on a leading trolley for each carrier has a retractable trolley dog which is normally driven by a chain dog projecting from a drive chain. The accumulator mechanism includes an actuator lever which is pivoted to mounting plates and carriers a cam roller that acts in a cam slot formed in a pivot plate. When the actuating lever is pivoted due to contacting a preceding carrier, the cam roller acts within the contour of the slot to pivotally displace the pivot plate. The pivot plate then pulls a lift link upwardly to pull on the pivot arm and retract the trolley dog from the chain dog. The slot is arranged to effect lost motion of the cam roller in the slot to accommodate over travel.

A shock-absorbing tow bar coupler is disclosed. The tow bar coupler includes a housing dimensioned and configured at forward end to engage a trolley of a power and free conveyor. At its rearward end, a clevis is disposed within and rotatably attached to the housing. A hitch dimensioned and configured to engage a tow bar is rotatably attached to the clevis. The tow bar hitch provides a resilient, shock-absorbing attachment between the trolley and the tow bar.

A stop mechanism for detaching a conveyor trolley from a drive system which normally drives the trolley along a conveyor track. A ramp can be moved into the path of a trolley dog so that the trolley dog moves upwardly along an inclined ramp surface to disengage the trolley dog from a drive dog carried by a driven chain of the conveyor system. The actuating mechanism for the ramp includes a pivotal cam plate actuated by a power cylinder. A cam slot in the cam plate receives a cam roller connected with a guide link which moves in a vertical guide slot. The guide link is connected with the ramp to move it up and down under the control of the actuating cylinder.

A center link pusher dog assembly for power and free conveyors includes a pusher dog member with a mounting base and a pusher dog projection upstanding therefrom. The mounting base has depending lugs and a rear shoulder to engage an abutment formed by a reduced central area of a center link of a conveyor chain. A bore through the pusher dog member recevies a bolt for clamping a center link between the pusher dog member and a conventional chain support type of power trolley. The lugs engage upstanding teeth on a mounting end of the power trolley and side walls of the center link to fix the longitudinal position of the pusher dog member relative to the power trolley and the center link and to fix its lateral position relative to the center link.